Regulation of Protein Degradation in Plants

Abstract

The dynamic state of proteins in higher plants has been known since the 1930s (1). The importance of protein degradation during seed germination and seedling establishment that allows utilization of proteinaceous reserves in seeds has been appreciated for some time and the study of this process has advanced significantly (2, 3). Although much work remains, for some seed storage proteins current studies in this area now focus on specific proteases and their cleavage specificity on native substrates (4–7). In contrast, our understanding of the molecular details of protein degradation and more importantly its regulation, in other aspects of plant metabolism, is less advanced. However, protein degradation is equally important in these other processes. An explanation for this discrepancy might be the greater complexity of proteolytic pathways, substrates and regulatory mechanisms operating both within a species and among higher plants compared to the process of seed storage protein degradation. In the latter case, even with a lower diversity of substrates, a battery of proteinases is required. This review will highlight the complexity of in vivo proteolysis.